Door-knob alarm



Get. 23

C. GRAEF DOOR KNOB ALARM Filed Jan. 17. 1923 Patented @ct. 23 1923.

STATES earner creme...

CARL L. GRAEF, OF HAWTHORNE, NEW JERSEY, ASSIGNOE OF ONE-HALF TO HERMANN KIND, OF NEW YORK, N. Y.

DOOR-KNOB ALARM.

Application filed January 17, 1923.

To all whom it may concern:

Be it known that I, CARL L. GRAEF, a citizen of the United States, and resident of Hawthorne, county of Passaic, and State of New Jersey, have invented certain new and useful Improvements in Door-Knob Alarms, of which the following is a specification.

This invention relates to an alarm associated with a door knob, supported entirely by the knob spindle, and constituting the inner knob thereof.

The invention has for one of its objects to provide a device of the character stated, simple in construction, positive and elfective in operation, and adapted to sound an alarm whenever the outer door knob is turned in either direction.

The invention has for its further object to provide a device having the foregoing capabilities, and adapted to be readily adjusted from an operative to an inoperative position, so that, when desired, the outer door knob may be free to be turned without sounding the alarm.

These objects, and others hereinafter stated, are accomplished by the means illustrated in the accompanying drawings, which embody the invention in its preferred form; but it is to be understood that the invention may be embodied in changes and modifications of the construction herein described having similar capabilities without departing from the invention.

In the drawings, in which similar reference numerals indicate corresponding parts throughout the several views;

Fig. 1 is a side elevation of a door knob alarm embodying the invention, applied to a door;

Fig. 2 is a front elevation, partly in section, of an inner knob which contains the alarm. mechanism the bell thereof being removed;

Fig. 3 represents a rear elevation of the alarm knob;

Fig. 1 represents a transverse section of the alarmknob on line l- 4c of Fig. 3;

Fig. 5 represents a back view of the alarm knob having the cover plate removed, and showing the automatic alarm actuating mechanism out of operative position;

Fig. 6 represents a view similar to that shown in Fig. 5 with the alarm mechanism in posit-ion for action when the knob is turned;

Serial No. 613,190.

Fig. 7 is a similar view showing the relative position of the bell, the releasing pendulum, and other parts when the alarm mechanism is operating; and

Fig. 8 is a perspective view of a duplex adjustable crank which controls the check pawl of the striking mechanism.

As illustrated in the drawings, the door knob itself comprises an outer casing, which may be of'a-ny suitable construction, for the purposes hereinafter specified, preferably having an inner cylindrical section 1, and an outer conical section 2, with a partition or wall 3, separating the interiors of those sections. The cylindrical wall of the section is shown provided with bosses 4:, having threaded apertures 5, that engage the threaded end of screw studs 6. The screw studs engage arc slots 7 formed in a back plate 8, which back plate is provided with hub 9 having an angular aperture 10 adapted to engage and be secured to a knob spindle of ordinary construction. By means of the screw studs 6 and the arc slots 7, the casing of the knob may be adjustably secured relatively to the back plate 8.

The cylindrical section is shown provided with an arc flange 11 extending beyond the margin of said section, so as to engage the inner wall of a flange 12 formed on the back plate 8. Smaller flanges 13 are also shown formed on the cylindrical section 1, which likewise engage the inner surface of the wall 12 of the back plate, said flanges being for the purpose of holding the cylindrical section against vertical and lateral movement of said section relative to the flange 12 of the back plate, and thereby aiding in holding the cylindrical section 1 and the back plate 8 in proper relation to each other.

The conical section 2 contains thestriking mechanism, which may be of ordinary construction. and the instance shown consists of a coil spring 14 having its outer end is arranged in operative relation with the rim of abell 23.

' llhe alarm control mechanism, which is the principal feature of this invention, embodies a weighted pendulum 25 having above its pivotal connection 26 an upwardly extending boss 27 that serves at times as a bearing for one free end 28 of a crank lever. The other free end 29 of said lever bears against the offset end of the double acting pawl 20, as shown in Fig. 2. The intermediate portion 30 of said lever is mounted in a bearing, of any suitable construction, connected with the casing or the interior wall 8 thereof.

While the free end 28 of the crank lever is above the bearing stud 27 and in the axial line of the pendulum 25, the train of gear Eng will be held against rotation, in the direction of striking an alarm, because of the fact that the other free end 29 of said lever holds the double acting pawl against movement in a striking direction.

An arc. plate 31 is slid'ingly mounted on the interior wall of the cylindrical section 1 by means of a stud 32 fixedly secured thereto, said stud being movable within a slot in the cylindrical section, as shown in Fig. 1.

'A stud 34- may be fixed to the wall of the cylindrical section 1 so as to engage a slot 85 formed in the arc plate 31., and guide the sliding movement of said plate 31 on the inner wall of the section 1 so as to hold it against lateral displacement relative thereto.

The are plate 31 is provided with a laterally ofi'set arm 35,'having an inclined tip 86 adapted to project beyond the bearing stud 27 of the pendulum when the striking mech anism is in inoperative position, as shown in Fig. 5 wherein the free end 28 of the crank lever isshown supported upon thetip 36 of the arm 35,

When it is desired to change the striking mechanism from the inoperative position, shown in Fig' 5, to an operative position, the arc plate 31 is moved to the left, the stud 32 sliding in the slot 33, until the arm 35 takes the position shown in Fig. 6 wherein the free end 28 of the crank lever is shown released from'the tip of the arm 35 and supported'upon the bearing boss 27 of the pendulum 25, which still holds the striking mechanism in an inoperative condition, but in a condition to be automatically operated, if the outer doorknob be turned either to the right or to the left.

The casing of the alarm knob being mounted upon the back plate 8, the hub 9 of which is secured to the spindle of the door knob, when the spindle is turned in one direction by the outer knob it will partially rotate the alarm knob so as to bring the parts into the positionshown in Fig. l

wherein the pendulum in adjusting its axial line to the perpendicular, to compensate for the changed position in casing, releases the free end 28,0f the lever from the bearing boss 27 of the pendulum, and at the same time releases the other free end 29 of the lever from the end of the double acting pawl 28, and the spring, which has been wound tightly, will then be free to uncoil and otate the driving gear 15, moving with it the train of gearing and permitting the tappet wheel 19 to vibrate the pawl 28 and the striker 21 connected therewith.

While Fig. 7 shows the position of the parts when the outer door knob is turned in one direction, the same result will be produced if the door knob be turned in the other direction, that is, the free end '28 of the crank lever would be released from the supporting stud and permit the spring to uncoil, and the striker to vibrate on the margin of the bell.

What I claim as new and desire to secure by Letters Patent is:

1. A door knob alarm, comprising a back plate having a spindle connection, a casing rotatably adjustable on said backplate, striking mechanism, a bell associated with said striking mechanism a spring actuated gear train operating said striking mechanism, a pivoted pendulum having a bearing stud, a duplex crank having one of its free ends adapted to bear on said stud, and having its other free end adapted to engage said striking mechanism, and act as a stop therefor and adjustable means for locking said striking mechanism in inoperative position.

2. A door knob alarm, comprising a back plate having a spindle connection, a casing rotatably adjustable on said back plate, striking mechanism within said casing, a bell associated with said striking mechanism, a spring actuated gear train operating said striking mechanism, a pivoted pendulum having a bearing stud, a duplex crank having one of its free'ends adapted to bear on said stud, and its other free end adapted to engage said striking mechanism and act as a stop therefor, and an arm slidingly adjustable on said casing and provided with a beveled tip adapted to engage and raise the first named free end of said lever 3. A door knobalarm, comprising a case ing having a spindle connection, striking mechanism within the casing, a bell associated with said striking mechanism, a spring actuated gear train operatingsaid striking mechanism, a pivoted pendulum having a bearing stud, a duplex crank ha-v ing one of its free ends adaptedto bear on said stud, and having its other free end adapted to engage said striking mechanism, and act as a stop therefor and an arm slidingly adjustable on said casing adapted to engage and raise one end of said lever.

raise the first named free end of said crank.

5. A door knob alarm, comprising a back plate having a spindle connection and provided with oppositely disposed arc slots, a casing provided with oppositely disposed studs engaging the slots of said back plate, striking mechanism having a double acting pawl, a bell associated with said striking mechanism, a spring actuated gear train operating said striking mechanism, a pivoted pendulum having a bearing stud, a duplex crank having one of its free ends adapted to bear on said stud, and its other free end adapted to engage said double acting pawl, and act as a stop for said striking mechanism and means for locking said crank in inoperative position.

6. A door knob alarm, comprising a back plate having'a spindle connection, a casing rotatably adjustable on said back plate and provided With an arc flange bearing against the inner surface of the Wall of said back plate, striking mechanism Within the casing, a bell associated with said striking IIlGCllZtnism, a pivoted pendulum having a bearing stud, a duplex crank having one of its free ends adapted to bear on said stud, and its other free end adapted to engage said strik ing mechanism and act as a stop therefor and means for setting said parts in inoperative position.

7. A door knob alarm, comprising a casing having a spindle connection, striking mechanism Within the casing, a bell associated with said striking mechanism, a spring actuated gear train operating said striking mechanism, a pivoted pendulum having a bearing stud, a duplex crank having one of its free ends adapted to bear on said stud, and its other free end adapted to engage said striking mechanism and act as a stop therefor, and an arc plate slidingly engaging the interior wall of said casing and provided with a stud and slot connection therewith, and having an arm provided with an inclined tip movable transversely of the axial line of said pendulum, to engage andraise the first named free end of said lever. In testimony that I claim the foregoing as my invention, I have signed my name hereunder.

CARL L. GRAEF. 

